The Byzantine Generals' Problem is like a really complicated game of "telephone" that computer scientists like to use to explain the challenges of distributed systems like blockchains.
Imagine you're a general in the Byzantine army, and you're trying to coordinate an attack on a city with your fellow generals. But here's the catch - some of the generals might be traitors who are trying to sabotage the attack by sending mixed messages. How do you make sure everyone's on the same page and not getting bamboozled?
That's basically what the Byzantine Generals' Problem is all about - how to reach consensus in a distributed system where not everyone can be trusted. Blockchains like Bitcoin solve this problem through a combination of cryptography, game theory, and good old-fashioned peer pressure.
Example
"I was trying to explain the Byzantine Generals' Problem to my date last night, but she just looked at me like I was speaking a foreign language. I guess not everyone finds distributed systems as sexy as I do."
"Sometimes I feel like the crypto community is just one big Byzantine Generals' Problem. Everyone's got their own agenda, and nobody knows who to trust."